This invention generally relates to percutaneous transluminal treatments and devices therefor. More specifically, the invention relates to improvements in catheter systems and treatment procedures including angioplasty for treating stenoses in blood vessels and other vessels of living bodies. A balloon-on-a-wire catheter device operates both as a balloon catheter and as a guidewire, which balloon-on-a-wire catheter also has a telescoping extension assembly therewithin. When the extension assembly is extended, the balloon-on-a-wire catheter operates as an extended guidewire that permits an over-the-wire percutaneous transluminal catheter to be guided therealong for treatments such as angioplasty treatment with a balloon having an expanded radial size larger than that of the balloon-on-a-wire catheter.
Percutaneous balloon angioplasty procedures are therapeutic medical treatments that can increase blood flow through a blood vessel or other body passageways exhibiting undesirable occlusions. As is well known, an elongated catheter having a deflated balloon at its distal end is guided through the body, such as through a patient's cardiovascular system to the coronary artery of the heart. Then, the balloon is inflated by a source of fluid under pressure originating outside of the body in order to compress deposits or plaque or undesired protrusions. For example, by this procedure, plaque can be compressed to an arterial wall, thereby dilating the stenosis or lesion.
Often balloon catheters cannot be negotiated easily through branching blood vessels to reach the location of the stenosis. Typically, surgeons assist in maneuvering these catheters by first inserting a more maneuverable guidewire through the vessel and branches and to the stenosis location. Then a balloon catheter is slidably inserted over the guidewire to and through the stenosis. After balloon inflation, the catheter and guidewire are removed. A limitation of this approach is that, in order to permit catheterization to be initiated, the stenosis must be open enough to permit insertion of the balloon catheter therethrough. Patients who exhibit particularly tight stenoses typically are obliged to undergo the risk and expense of heart bypass surgery, for example. At other times, the stenosis is such that, after insertion of a first balloon catheter and most likely after catheterization has been effected with this balloon, the surgeon determines a different catheter is needed for the particular procedure. Thus, in certain procedures, it is necessary to exchange catheters to treat a single lesion and/or multiple lesions within the same vessel. In those instances, it is desirable to avoid having to retract the guidewire tip from its position distal of the lesion before the time when treatment is completed. For example, if the guidewire is removed from (passed proximally of) the lesion, the passageway (which may already be very limited in size) may close due to a blood vessel spasm so that the guidewire cannot again safely be pushed through the lesion.
Extendable guidewires have been suggested for introducing a dilatation catheter into a cardiovascular system. Such an extendable guidewire has a guidewire section and an extension section with a connection for joining the two sections together. The guidewire section is used for positioning the catheter within the subject, and the extension section is used to extend the length of the guidewire in order to exchange catheters. Included in this regard are U.S. Pat. No. 4,827,941 and No. 4,846,193, the latter guidewire having first and second interfitting sections movable between an extended and a retracted position.
Approaches such as those of U.S. Pat. No. 4,846,174 and No. 5,102,390 call for insertion of a guidewire so that its tip is distal of the lesion, followed by insertion of a balloon catheter to the lesion location. If the lesion is too occluded to permit insertion of the uninflated balloon catheter, approaches such as these call for removal of the guidewire through the lumen of the balloon catheter while holding the balloon catheter on the proximal side of the stenosis. The surgeon then inserts a microdilation probe, dilating guidewire, or similar device through the lumen of the balloon catheter and to the lesion. The balloon of the probe or dilating guidewire is inflated in order to create an opening sufficiently large to permit insertion of the balloon catheter therethrough to effect further dilation of the lesion.
In summary, the present invention provides a balloon-on-a-wire catheter having an extension assembly within its lumen, the extension assembly having an elongated core wire which can be pulled out of the lumen to, in effect, provide an elongated guidewire that will accept an over-the-wire percutaneous transluminal balloon catheter. With this structure, the balloon-on-a-wire catheter can be transluminally threaded to the location of a lesion by the use of a suitable control handle or the like. Thereafter, the control handle is removed while the balloon-on-a-wire catheter remains placed at the lesion in order to thereby gain access to the proximal end of the extendable core wire which is then pulled and extended. An over-the-wire catheter can then be slid over the extended core wire and the balloon-on-a-wire catheter for treatment as needed in addition to that provided by the balloon-on-a-wire catheter.
It is a general object of the present invention to provide an improved balloon-on-a-wire catheter which is extendable, a kit of parts including same and an over-the-wire catheter, and a treatment procedure utilizing same.
Another object of the present invention is to provide an improved balloon-on-a-wire catheter which is extendable in a proximal direction without disturbing the positioning of the distal end of the balloon-on-a-wire catheter and without requiring attachment of an extending member thereto.
Another object of the present invention is to facilitate a percutaneous transluminal treatment procedure wherein the number of steps required to perform an angioplasty procedure is reduced in an arrangement that avoids having a guidewire type of member pass distally of a lesion more than once during the entire procedure.
Another object of this invention is to improve the ability for a balloon-on-a-wire catheter to be used both as a stenosis treating device and as a guidewire for another catheter device without requiring any additional components or attachments.
These and other objects, features and advantages of this invention will be clearly understood through a consideration of the following detailed description.